Doug Pearson, the district's director of building services, says what was applied at more than a dozen city schools was not pesticides but herbicides, to kill weeds on sidewalks and along fences. The once-yearly application was done at a time when fewer people were present, and authorized by the school board, as required. But the state classifies herbicides as pesticides and requires use of these signs.

At the playfield by O'Keeffe Elementary last Thursday, the signs prompted one woman to shoo people off the field, exclaiming "Can you believe they've done this?" And Bert Zipperer, a school employee and neighborhood resident, is not consoled by the district's explanation: "Agent Orange was just a herbicide, too."